EUVD-2025-10386

Comprehensive Technical Analysis of EUVD-2025-10386

1. Vulnerability Assessment and Severity Evaluation

The vulnerability described in EUVD-2025-10386 affects the HAX CMS PHP application, specifically within its file upload functionality. The issue arises from the use of a non-exhaustive denylist to block certain file types, which can lead to a "fail open" scenario. This means that if a file type is not explicitly blocked, it can be uploaded to the server, potentially leading to unauthorized code execution or other malicious activities.

Severity Evaluation:

• CVSS Base Score: 10.0 (Critical)
• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

The high base score indicates that this vulnerability is critical. The attack vector (AV:N) is network-based, requiring low complexity (AC:L) and low privileges (PR:L). No user interaction (UI:N) is needed, and the scope (S:C) is changed, affecting confidentiality, integrity, and availability (C:H/I:H/A:H).

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

1. Unauthorized File Upload: An attacker could upload files with extensions not included in the denylist, such as .py, .pl, or .exe, which could then be executed on the server.
2. Web Shell Upload: By uploading a web shell, an attacker could gain remote access to the server, allowing them to execute arbitrary commands.
3. Data Exfiltration: An attacker could upload a script that reads sensitive files from the server and sends them to a remote location.

Exploitation Methods:

1. Direct File Upload: An attacker could directly upload a malicious file through the vulnerable file upload functions.
2. Phishing Attacks: An attacker could trick a user into uploading a malicious file through social engineering techniques.
3. Automated Scripts: An attacker could use automated scripts to probe the file upload functionality and identify vulnerable endpoints.

3. Affected Systems and Software Versions

Affected Systems:

• HAX CMS PHP application versions 9.0.0 through 10.0.2.

Software Versions:

• Versions prior to 10.0.3 are vulnerable.
• The vulnerability is fixed in version 10.0.3.

4. Recommended Mitigation Strategies

1. Immediate Patching: Upgrade to HAX CMS PHP version 10.0.3 or later, which includes the fix for this vulnerability.
2. Whitelisting: Implement a whitelist approach for file uploads, allowing only specific file types that are necessary for the application's functionality.
3. Input Validation: Enhance input validation to ensure that only safe files are uploaded.
4. Regular Audits: Conduct regular security audits and code reviews to identify and mitigate similar vulnerabilities.
5. Monitoring: Implement monitoring and logging to detect and respond to any suspicious file upload activities.

5. Impact on European Cybersecurity Landscape

The vulnerability poses a significant risk to organizations using the HAX CMS PHP application within the European Union. Given the critical nature of the vulnerability, it could lead to widespread data breaches, unauthorized access, and potential disruption of services. The European Network and Information Security Agency (ENISA) and other cybersecurity authorities should issue advisories to raise awareness and encourage immediate patching.

6. Technical Details for Security Professionals

Vulnerable Code: The vulnerability is located in the save function within HAXCMSFile.php. The current denylist only blocks .php, .sh, .js, and .css files, leaving other potentially dangerous file types unblocked.

Example of Vulnerable Code:

function save($file) {
    $denylist = ['.php', '.sh', '.js', '.css'];
    $fileExtension = pathinfo($file, PATHINFO_EXTENSION);
    if (!in_array($fileExtension, $denylist)) {
        // Proceed with file upload
    } else {
        // Block file upload
    }
}

Recommended Fix: Implement a whitelist approach to restrict file uploads to safe file types.

Example of Fixed Code:

function save($file) {
    $whitelist = ['.jpg', '.png', '.gif', '.pdf'];
    $fileExtension = pathinfo($file, PATHINFO_EXTENSION);
    if (in_array($fileExtension, $whitelist)) {
        // Proceed with file upload
    } else {
        // Block file upload
    }
}

Additional Security Measures:

• File Scanning: Implement file scanning mechanisms to detect and block malicious files.
• Access Controls: Enforce strict access controls to limit who can upload files.
• Encryption: Ensure that sensitive data is encrypted both in transit and at rest.

By addressing this vulnerability promptly and comprehensively, organizations can significantly reduce the risk of exploitation and protect their digital assets.